Method of colouring and lightening keratin materials in the presence of a reducing agent comprising a fluorescent disulphide dye

ABSTRACT

The invention relates to a dyeing composition comprising a fluorescent disulfide dye and to a method of dyeing keratin materials, with a lightening effect, that employs said composition. It likewise relates to new fluorescent disulfide dyes and to their uses in the lightening of keratin materials. The composition allows a particularly persistent lightening effect to be obtained.

This application is a divisional application of U.S. application Ser.No. 12/282,586 filed on Jul. 1, 2009, now a U.S. Pat. No. 8,038,731 B2,which is a National Phase application based on PCT/FR2007/051008 filedon Mar. 23, 2007, and which claims the priority of French ApplicationNo. 0651035, filed on Mar. 24, 2006, and the benefit of U.S. ProvisionalApplication No. 60/792,941, filed on Apr. 19, 2006.

The invention relates to a method of colouring and lightening keratinmaterials in the presence of a reducing agent.

Dyeing of keratin fibres, particularly human keratin fibres, by directdyeing is known. The method conventionally used in direct dyeinginvolves applying direct dyes to the keratin fibres, said dyes beingcoloured and colouring molecules which have an affinity for the fibres,allowing said dyes to diffuse, and then rinsing the fibres.

The direct dyes which are conventionally used are, for example,nitrobenzene dyes, anthraquinone dyes, nitropyridine dyes or azo,xanthene, acridine, azine or triarylmethane dyes.

The dyeings which result from the use of direct dyes are temporary orsemi-permanent dyeings, since the nature of the interactions that bindthe direct dyes to the keratin fibre, and their desorption from thesurface and/or from the core of the fibre, are responsible for theirweak dyeing power and their poor fastness to washing or perspiration.

Furthermore, the dyeing of keratin fibres on the basis of conventionaldirect dyes does not allow the keratin fibres to be significantlylightened.

The lightening of the colour of keratin fibres, more particularly ofdark keratin fibres, towards lighter shades, by modifying the shade ofthese fibres where appropriate, constitutes a major demand.

Conventionally, in order to obtain a lighter dyeing, a chemicalbleaching method is employed. This method involves treating the keratinmaterials such as the keratin fibres, more particularly the hair, with astrong oxidizing system, generally composed of hydrogen peroxide,combined or not with persalts, typically in an alkaline medium.

This bleaching system has the drawback of degrading the fibres andimpairing their cosmetic properties. Specifically, the fibres tend tobecome coarse, more difficult to disentangle and more fragile. Finally,the lightening or bleaching of keratin fibres on the basis of anoxidizing agent is incompatible with treatments for modifying the shapeof said fibres, particularly in straightening treatments.

Another lightening technique involves applying fluorescent direct dyesto dark hair. This technique, described more particularly in thedocument FR 2830189, allows the quality of the keratin fibre to berespected in the course of the treatment; however, the fluorescent dyesthat are employed are not satisfactorily resistant to shampooing.

In order to enhance the persistence of direct dyeings, the fixing of thedirect dyes to the hair by covalent bonding is known. It is known forexample, to react dyes containing reactive groups with the cystine orcysteine residues which are very numerous in keratin fibres. Hencecertain dyes have been described that carry Bunte salt and isothiuroniumfunctions or other thiol-protecting groups. However, obtaining thereactive form of the dye generally necessitates the use of stronglybasic media. Moreover, the thiol functions are generally generated inexcess, thereby necessitating a step of subsequent neutralizationfollowing dyeing.

Other disulphide dyes known for the dyeing of keratin fibres aredisulphide derivatives of aminothiophenol derivatives. Such dyes aredescribed, for example, in patent FR 1156407. These dyes may be usedunder relatively gentle conditions, in the presence of a slightlyreducing medium or after a reducing pretreatment on the hair. Thesedyes, however, may give rise to unwanted colour changes on application.

Finally, the document WO 2005/097051 describes azaimidazolium disulphidedyes for the direct dyeing of keratin fibres.

The aim of the present invention is to provide new systems for dyeingkeratin materials with a lightening effect, especially human keratinfibres, particularly the hair, that do not have the drawbacks of theexisting bleaching methods. More particularly, one of the aims of thepresent invention is to provide systems for direct colouring that allowlightening effects to be obtained more particularly on naturally orartificially dark keratin fibres, these effects being persistent inresponse to successive shampooings, without detriment to the keratinfibres and without impairing their cosmetic properties.

This aim is achieved with the present invention, which provides a methodof colouring dark keratin materials that involves applying to thekeratin materials a dyeing composition comprising in an appropriatecosmetic medium at least one fluorescent disulphide dye for exampleselected from the dyes of formulae (I) and (II) below:A-(X)_(p)—C_(sat)—S—S—C′_(sat)—(X′)_(p′)-A′  (I)A-(X)_(p)—C_(sat)—S—S—C′_(sat)—(X′)_(p′)-D  (II),their organic or inorganic acid salts, optical isomers, geometricalisomers, and the solvates such as hydrates,in which formulae:

-   -   A and A′, which are identical or different, each represent a        radical containing at least one cationic or non-cationic        fluorescent chromophore;    -   X and X′, which are identical or different, each represent a        saturated or unsaturated, linear or branched C₁-C₃₀ hydrocarbon        chain which is optionally interrupted and/or optionally        terminated at one or two of its ends by one or more divalent        groups or combinations thereof selected from:        -   —N(R)—, —N⁺(R)(R), —O—, —S—, —CO—, —SO₂— where R and R′,            which are identical or different, are each selected from a            hydrogen or a C₁-C₄ alkyl, hydroxyalkyl or aminoalkyl            radical;        -   a saturated or unsaturated, fused or non-fused, aromatic or            non-aromatic (hetero)cyclic radical optionally comprising            one or more identical or non-identical heteroatoms and            optionally substituted;    -   the coefficients p and p′, which are identical or different,        each represent an integer equal to 0 or 1;    -   C_(sat) and C′_(sat), which are identical or different, each        represent an optionally cyclic, optionally substituted, linear        or branched C₁-C₁₈ alkylene chain;    -   D corresponds to a radical selected from hydroxyl, hydroxyalkyl,        alkoxy, carboxyl, carboxylate, amino, alkylamino and        dialkylamino radicals; this application is performed in the        presence of a reducing agent.

This reducing agent may be selected from thiols, for example cysteine,homocysteine, thiolactic acid, the salts of these thiols, phosphines,bisulphite, sulphites, thioglycolic acid, and also its esters,particularly glycerol monothioglycolate, and thioglycerol.

This reducing agent may also be selected from borohydrides and theirderivatives, such as, for example, borohydride, cyanoborohydride,triacetoxyborohydride and trimethoxyborohydride salts: sodium, lithium,potassium, calcium, quaternary ammonium (tetramethylammonium,tetraethylammonium, tetra-n-butylammonium and benzyltriethylammonium)salts; and catecholborane.

The method of the invention allows lightening of dark keratin materialsto be obtained. In particular the method of the invention allows keratinfibres such as the hair to be lightened in a way which is verypersistent in response to shampooing, to common harsh influences (sun,perspiration) and to other hair treatments, without degrading thekeratin fibre.

For the purposes of the invention a dark keratin material is one whichexhibits a lightness L* in the C.I.E. L*a*b* system of less than orequal to 45 and preferably less than or equal to 40, where an L* of 0corresponds to black and an L* of 100 to white.

For the purposes of the invention, hair which is naturally orartificially dark is hair whose tone level is less than or equal to 6(dark blond) and preferably less than or equal to 4 (brown).

The lightening of the hair is evaluated via the “tone level”, whichcharacterizes the degree or level of lightening. The “tone” concept isbased on the classification of natural shades, with one tone separatingeach shade from its immediate precursor or successor. This definition,and the classification of the natural shades, is well known to haircareprofessionals and is published in the work “Science des traitementscapillaires” by Charles ZVIAK, Masson, 1988, pages 215 and 278.

The tone levels range from 1 (black) to 10 (light light blond), one unitcorresponding to one tone; the higher the number the lighter the shade.

Artificially coloured hair is hair whose colour has been modified by adyeing treatment, for example dyeing with direct dyes or oxidation dyes.

Preferably, following application to hair, brown hair for example, thecomposition must lead to the results below.

-   -   The parameter of interest is the reflectance performances of the        hair when irradiated with visible light in the wavelength range        from 400 to 700 nanometres.    -   The curves of reflectance as a function of wavelength are then        compared for hair treated with the composition of the invention        and untreated hair.    -   The curve corresponding to the treated hair is required to show        a reflectance in the wavelength range from 450 to 700 nanometres        which is greater than the curve corresponding to the untreated        hair.    -   This means that, in the wavelength range from 450 to 700        nanometres, there is at least one range in which the reflectance        curve corresponding to the treated hair is higher than the        reflectance curve corresponding to the untreated hair. By        “higher” is meant a difference of at least 0.05% reflectance,        and preferably at least 0.1%. This is not to rule out the        possibility that, within the wavelength range from 450 to 700        nanometres, there is at least one range in which the reflectance        curve corresponding to the treated hair is either superimposable        on or lower than the reflectance curve corresponding to the        untreated hair.

The wavelength of maximum difference between the reflectance curve ofthe treated hair and that of the untreated hair is preferably situatedwithin the wavelength range from 450 to 650 nanometres, and preferablyin the wavelength range from 450 to 620 nanometres.

For the purposes of the present invention, and in the absence of anyindication to the contrary:

-   -   a fluorescent disulphide dye is a fluorescent compound        containing at least one fluorescent chromophore as defined        hereinafter and containing one or more S—S disulphide bonds        between two carbon atoms which are connected directly or        indirectly to the fluorescent chromophore(s) of the compound;        preferably the bond is capable of being reduced in a        cosmetically acceptable medium;    -   the “aryl” or “heteroaryl” radicals or the aryl or heteroaryl        moiety of a radical may be substituted by at least one        substituent carried by a carbon atom and selected from:        -   a C₁-C₁₆, preferably C₁-C₈, alkyl radical which is            optionally substituted by one or more radicals selected from            the following radicals: hydroxyl, C₁-C₂ alkoxy, C₂-C₄            (poly)-hydroxyalkoxy, acylamino, amino substituted by two,            identical or different, C₁-C₄ alkyl radicals which            optionally carry at least one hydroxyl group, it being            possible for the two radicals to form, with the nitrogen            atom to which they are attached, a heterocycle containing 5            to 7 members, preferably 5 or 6 members, which is saturated            or unsaturated and optionally substituted and optionally            comprises another heteroatom identical to or different from            the nitrogen;        -   a halogen atom such as chlorine, fluorine or bromine;        -   a hydroxyl group;        -   a C₁-C₂ alkoxy radical; a C₂-C₄ (poly)-hydroxyalkoxy            radical;        -   an amino radical;        -   a 5- or 6-membered heterocycloalkyl radical;        -   a 5- or 6-membered heteroaryl radical which is optionally            cationic, preferably imidazolium, and is optionally            substituted by a (C₁-C₄)alkyl radical, preferably methyl;        -   an amino radical substituted by one or two identical or            different C₁-C₆ alkyl radicals which optionally carry at            least:            -   i) a hydroxyl group,            -   ii) an amino group which is optionally substituted by                one or two, optionally substituted C₁-C₃ alkyl radicals,                it being possible for said alkyl radicals to form, with                the nitrogen atom to which they are attached, a                heterocycle containing 5 to 7 members which is saturated                or unsaturated, optionally substituted and optionally                comprises at least one other heteroatom different or not                from nitrogen,            -   iii) a quaternary ammonium group —N⁺R′R″R′″, M⁻ for                which R′, R″ and R′″, which are identical or different,                each represent a hydrogen atom or a C₁-C₄ alkyl group;                and M⁻ represents the counterion of the corresponding                halide or organic or inorganic acid,            -   iv) or a 5- or 6-membered heteroaryl radical which is                optionally cationic, preferably imidazolium, and is                optionally substituted by a (C₁-C₄)alkyl radical,                preferably methyl;        -   an acylamino radical (—NR—COR′) in which the radical R is a            hydrogen atom or a C₁-C₄ alkyl radical which optionally            carries at least one hydroxyl group and the radical R′ is a            C₁-C₂ alkyl radical; a carbamoyl radical ((R)₂N—CO—) in            which the radicals R, which are identical or not, each            represent a hydrogen atom or a C₁-C₄ alkyl radical which            optionally carries at least one hydroxyl group; an            alkylsulphonylamino radical (R′SO₂—NR—) in which the radical            R represents a hydrogen atom or a C₁-C₄ alkyl radical which            optionally carries at least one hydroxyl group, and the            radical R′ represents a C₁-C₄ alkyl radical or a phenyl            radical; an aminosulphonyl radical ((R)₂N—SO₂—) in which the            radicals R, which are identical or not, each represent a            hydrogen atom or a C₁-C₄ alkyl radical which optionally            carries at least one hydroxyl group,        -   a carboxyl radical in acid form or salified form (preferably            with an alkali metal or a substituted or unsubstituted            ammonium);        -   a cyano group (CN);        -   a polyhaloalkyl group, preferably trifluoromethyl (CF₃);    -   the cyclic or heterocyclic moiety of a non-aromatic radical may        be substituted by at least one substituent carried by a carbon        atom and selected from the following groups:        -   hydroxyl,        -   C₁-C₄ alkoxy, C₂-C₄ (poly)hydroxyalkoxy,        -   alkylcarbonylamino ((RCO—NR′—) in which the radical R′ is a            hydrogen atom or a C₁-C₄ alkyl radical which optionally            carries at least one hydroxyl group, and the radical R is a            C₁-C₂ alkyl radical, amino substituted by two identical or            different C₁-C₄ alkyl groups which optionally carry at least            one hydroxyl group, it being possible for said alkyl            radicals to form, with the nitrogen atom to which they are            attached, a heterocycle containing 5 to 7 members which is            saturated or unsaturated, is optionally substituted and            optionally comprises at least one other heteroatom,            different or not from nitrogen;        -   alkylcarbonyloxy ((RCO—O—) in which the radical R is a C₁-C₄            alkyl radical, amino substituted by two identical or            different C₁-C₄ alkyl groups which optionally carry at least            one hydroxyl group, it being possible for said alkyl            radicals to form, with the nitrogen atom to which they are            attached, a heterocycle containing 5 to 7 members which is            saturated or unsaturated, is optionally substituted and            optionally comprises at least one other heteroatom,            different or not from nitrogen;        -   alkoxycarbonyl ((RO—CO—) in which the radical R is a C₁-C₄            alkyl radical, amino substituted by two identical or            different C₁-C₄ alkyl groups which optionally carry at least            one hydroxyl group, it being possible for said alkyl            radicals to form, with the nitrogen atom to which they are            attached, a heterocycle containing 5 to 7 members which is            saturated or unsaturated, is optionally substituted and            optionally comprises at least one other heteroatom,            different or not from nitrogen;    -   a cyclic or heterocyclic radical or a non-aromatic moiety of an        aryl or heteroaryl radical may also be substituted by one or        more oxo groups;    -   a hydrocarbon chain is unsaturated when it contains one or more        double bonds and/or one or more triple bonds;    -   an “aryl” radical represents a fused or non-fused monocyclic or        polycyclic group which contains 6 to 22 carbon atoms and        includes at least one aromatic ring; preferably the aryl radical        is a phenyl, biphenyl, naphthyl, indenyl, anthracenyl or        tetrahydronaphthyl;    -   a “heteroaryl radical” represents a fused or non-fused,        optionally cationic, monocyclic or polycyclic group containing 5        to 22 members, 1 to 6 heteroatoms selected from nitrogen,        oxygen, sulphur and selenium atoms, and including at least one        aromatic ring; preferably a heteroaryl radical is selected from        acridinyl, benzimidazolyl, benzobistriazolyl, benzopyrazolyl,        benzopyridazinyl, benzoquinolyl, benzothiazolyl, benzotriazolyl,        benzoxazolyl, pyridinyl, tetrazolyl, dihydrothiazolyl,        imidazopyridinyl, imidazolyl, indolyl, isoquinolyl,        naphthoimidazolyl, naphthooxazolyl, naphthopyrazolyl,        oxadiazolyl, oxazolyl, oxazolopyridyl, phenazinyl,        phenooxazolyl, pyrazinyl, pyrazolyl, pyrilyl, pyrazoyltriazyl,        pyridyl, pyridinoimidazolyl, pyrrolyl, quinolyl, tetrazolyl,        thiadiazolyl, thiazolyl, thiazolopyridinyl, thiazoylimidazolyl,        thiopyrylyl, triazolyl, xanthylyl and its ammonium salt;    -   a “cyclic radical” is a fused or non-fused, monocyclic or        polycyclic, non-aromatic cycloalkyl radical containing 5 to 22        carbon atoms and able to contain from 1 to a plurality of        unsaturations:    -   a “heterocyclic radical” is a fused or non-fused, monocyclic or        polycyclic, non-aromatic radical containing 5 to 22 members and        containing 1 to 6 heteroatoms selected from nitrogen, oxygen,        sulphur and selenium atoms;    -   an “alkyl radical” is a linear or branched, C₁-C₁₆, preferably        C₁-C₈ hydrocarbon radical;    -   the expression “optionally substituted” attributed to the alkyl        radical means that said alkyl radical may be substituted by one        or more radicals selected from the following radicals: i)        hydroxyl, ii) C₁-C₄ alkoxy, iii) acylamino, iv) amino optionally        substituted by one or two identical or different C₁-C₄ alkyl        radicals, it being possible for said alkyl radicals to form,        with the nitrogen atom which carries them, a heterocycle        containing 5 to 7 members and optionally comprising another        heteroatom which is different or not from nitrogen; v) or a        quaternary ammonium group —N⁺R′R″R′″, M⁻ for which R′, R″ and        which are identical or different, each represent a hydrogenatom        or a C₁-C₄ alkyl group, or —N⁺R′R″R′″ forms a heteroaryl such as        imidazolium which is optionally substituted by a C₁-C₄ alkyl        group, and M⁻ represents the counterion of the corresponding        halide, organic or inorganic acid;    -   an “alkoxy radical” is an alkyl-oxy radical for which the alkyl        radical is a C₁-C₁₆, preferably C₁-C₈, linear or branched        hydrocarbon radical;        when the alkoxy group is optionally substituted, this means that        the alkyl group is optionally substituted as defined above.

Moreover, unless indicated otherwise, the top and bottom valuesdelimiting the extent of a range of values are included within saidrange of values.

According to the present invention a “fluorescent chromophore” is aradical obtained from a fluorescent compound. A fluorescent compound isa compound which is capable of absorbing UV or visible radiation at awavelength λ_(abs) between 250 and 800 nm and capable of re-emitting inthe visible range at an emission wavelength λ_(em) of between 400 and800 nm.

The fluorescent compounds are preferably dyes which are capable ofabsorbing λ_(abs) between 400 and 800 nm in the visible and ofre-emitting λ_(em) between 400 and 800 nm in the visible. Morepreferably the fluorescent dyes are dyes which are capable of absorbingat a λ_(abs) of between 420 nm and 550 nm and of re-emitting in thevisible at a λ_(em) of between 470 and 600 nm.

I. Dyes of Formulae (I) and (II)

The radicals A and A′ of the formulae (I) and (II) may contain one ormore identical or different fluorescent chromophores.

I.1. Chromophores

For the purposes of the present invention the chromophores are said tobe different when they differ in their chemical structure. Suchchromophores may be chromophores obtained from different classes or froma single class but having different chemical structures. For example,the chromophores may be selected from the class of the (poly)methinedyes but may differ in the chemical structure of the radicalsconstituting them or in the respective position of these radicals.

Fluorescent chromophores which are useful in the present inventioninclude the radicals obtained from acridine, acridone, benzanthrone,benzimidazole, benzimidazolone, benzindole, benzoxazole, benzopyran,benzothiazole, coumarin,difluoro{2-[(2H-pyrrol-2-ylidene-kN)methyl]-1H-pyrrolato-kN}boron(BODIPY®), dipyrrinone, diketopyrrolopyrrole, fluorindine, (poly)methine(particularly cyanine and styryl/hemicyanine), naphthalimide,naphthanilide, naphthylamine (such as the dansyls), oxadiazole, oxazine,perilone, perinone, perylene, polyene/carotenoid, squarane, stilbene andxanthene dyes.

Mention may also be made of the fluorescent dyes that are described inthe documents EP 1133975, WO 03/029359, EP 860636, WO 95/01772, WO95/15144 and EP 714954, and those listed in the encyclopaedia “Thechemistry of synthetic dyes” by K. VENKATARAMAN, 1952, Academic Press,Volumes 1 to 7, in the encyclopaedia “Kirk Othmer” Chemical technology,“Dyes and dye intermediates” chapter, 1993, Wiley and Sons, and invarious chapters of the encyclopaedia “ULLMANN's ENCYCLOPEDIA ofIndustrial Chemistry”, 7th Edition, Wiley and Sons, and in TheHandbook—A Guide to Fluorescent Probes and Labeling Technologies, 10thEdition, Molecular Probes/Invitrogen—Oregon 2005, distributed on theInternet or in the previous printed editions.

Preferably the chromophores are selected from those obtained from dyesof coumarin, (poly)methine (more particularly cyanine andstyryl/hemicyanine) and naphthalimide types.

In one variant the radicals A and A′ of the formulae (I) or (II) containat least one cationic radical which is carried by or included in atleast one of the chromophores.

Preferably the cationic radical is a quaternary ammonium.

These cationic radicals are, for example, an alkylammonium, acridinium,benzimidazolium, benzobistriazolium, benzopyrazolium, benzopyridazinium,benzoquinolium, benzothiazolium, benzotriazolium, benzoxazolium,bipyridinium, bistetrazolium, dihydrothiazolium, imidazopyridiniurn,imidazolium, indolium, isoquinolium, naphthoimidazolium,naphthooxazolium, naphthopyrazolium, oxadiazolium, oxazolium,oxazolopyridinium, oxonium, phenazinium, phenooxazolium, pyrazinium,pyrazolium, pyrazoyltriazolium, pyridinium, pyridinoimidazolium,pyrrolium, pyrylium, quinolium, tetrazolium, thiadiazolium, thiazolium,thiazolopyridinium, thiazoylimidazolium, thiopyrylium, triazolium orxanthylium radical.

I.2. C_(sat) and C′_(sat):

As indicated previously, in the formulae (I) or (II), C_(sat) andC′_(sat), independently of one another, represent an optionally cyclic,optionally substituted, linear or branched C₁-C₁₈ alkylene chain.Substituents include amino (C₁-C₄)alkylamino or (C₁-C₄)dialkylaminogroups or the group R^(a)—Z^(a)—C(Z^(b))—(in which Z^(a) and Z^(b),which are identical or different, each represent an oxygen or sulphuratom or a group NR^(a)′, and R^(a) represents an alkali metal, ahydrogen atom or a C₁-C₄ alkyl group and R^(a)′ represents a hydrogenatom or a C₁-C₄ alkyl group), which are present preferably on the carbonin the position beta or gamma to the sulphur atoms.

Preferably, in the case of the formulae (I) or (II), C_(sat) andC′_(sat) represent a chain —(CH₂)_(k)— where k is an integer of between1 and 8 inclusive.

I.3. X and X′:

In accordance with one particular embodiment of the invention, in theformulae (I) or (II) above, when p is 1, X and X′, which are identicalor different, each represent the following sequence:-(T)_(t)-(Z)_(z)-(T′)_(t′)-said sequence being connected in the formulae (I) or (II) symmetricallyas follows:—C_(sat)(or C′_(sat))-(T)_(t)-(Z)_(z)-(A or A′); in which

T and T′, which are identical or different, each represent one or moreradicals or combinations thereof selected from the following: —SO₂—;—O—; —S—; —N(R)—; —N⁺(R)(R^(o))—; —CO—; where R and R^(o), which areidentical or different, each represent a hydrogen atom or a C₁-C₄ alkyl,C₁-C₄ hydroxyalkyl or aryl(C₁-C₄)alkyl radical; and a preferablymonocyclic, cationic or non-cationic, heteroaryl or heterocycloalkylradical containing preferably two heteroatoms (more preferably twonitrogen atoms) and containing preferably 5 to 7 members, morepreferably imidazolium;

the indices t and t′, which are identical or different, are each 0 or 1;

Z represents:

-   -   —(CH₂)_(m)— where m is an integer between 1 and 8    -   (CH₂CH₂O)_(q)— or —(OCH₂CH₂)_(q)— in which q is an integer        between 1 and    -   an aryl, alkylaryl or arylalkyl radical in which the alkyl        radical is C₁-C₄ and the aryl radical is preferably C₆, this        radical being optionally substituted by at least one group SO₃M        where M represents a hydrogen atom, an alkali metal or an        ammonium group substituted by one or more identical or        non-identical, linear or branched, C₁-C₁₈ alkyl radicals which        optionally carry at least one hydroxyl        z is 0 or 1.

Furthermore, according to one particular embodiment of the invention, Zrepresents:

I.4. Fluorescent Disulphide Dyes:

In one preferred variant of the invention the disulphide dye is acationic fluorescent dye comprising at least one quaternary ammoniumradical and being such that, in the formula (I) with p being 1:

A and A′, which are identical or different, more preferably identical,each represent W—C(R^(c))═C(R^(d))—Ar— or —W—C(R^(c))═C(R^(d))—Ar, whereW represents a heterocycle or a heteroaryl containing a quaternaryammonium; Ar represents a 5- or 6-membered (hetero)aryl radical ofphenyl or pyridinium type, or a (hetero)aromatic bicyclic system ofnaphthyl, benzopyridinium, indolinyl or benzoindolinyl type, which areoptionally substituted by one or more halogen atoms, preferablychlorine, fluorine; by one or more alkyl groups, preferably C₁-C₄ alkylgroups; by one or more hydroxyl groups; by one or more alkoxy groups, byone or more hydroxyalkyl groups, by one or more amino or (di)alkylaminogroups, preferably with the alkyl moiety being C₁-C₄, by one or moreacylamino groups; by one or more 5- or 6-membered heteroaryl orheterocycloalkyl groups selected preferably from pyrrolidinyl,piperazinyl, piperidinyl and imidazolinyl; 13′ and R^(d), which areidentical or different, each represent a hydrogen atom or a C₁-C₄ alkylgroup.

In one preferred variant p, p′=1; z=0; t′=0 and t=1, and T represents—N(R)—, preferably in the para position on Ar relative to the olefinfunction —C(R^(c))═C(R^(d))—.

In another preferred variant p, p′=1; z=0; t, t′=1; T represents —N(R)—,preferably in the para position on Ar relative to the olefin function—C(R^(c))═C(R^(d))— and T′ represents a group —N(R)—, —N⁺(R)(R^(o)) oran imidazolium.

Preferably W is an imidazolium, pyridinium, benzopyridinium,benzimidazolium, quinolinium and pyrazolium which are optionallysubstituted by one or more identical or non-identical C₁-C₄ alkylradicals.

In another preferred variant the disulphide dye is a cationicfluorescent dye containing at least one quaternary ammonium radical andsuch that, in the formula (I) with p being 1:

A represents a naphthalimidyl radical of the formula:

represents the bond with the group X or X′, C_(sat) or C′_(sat),

wherein R^(e), R^(f), R^(g) and R^(h), which are identical or different,each represent a hydrogen atom or an optionally substituted C₁-C₆ alkylgroup.

More preferably the disulphide dye is a fluorescent dye selected from:

in which

-   -   G and G′, which are identical or different, each represent a        group —NR_(c)R_(d), —NR′_(c)R′_(d) or optionally substituted,        preferably unsubstituted, C₁-C₆ alkoxy; preferably G and G′        represent respectively a group —NR_(c)R_(d) and    -   R_(a) and R′_(a), which are identical or different, represent an        aryl(C₁-C₄)alkyl group or a C₁-C₆ alkyl group which is        optionally substituted by a hydroxyl or amino group, C₁-C₄        alkylamino or C₁-C₄ dialkylamino, it being possible for said        alkyl radicals to form, with the nitrogen atom which carries        them, a heterocycle containing from 5 to 7 chain members,        optionally comprising another heteroatom different or not        different from nitrogen; preferably R_(a) and R′_(a) represent a        C₁-C₃ alkyl group which is optionally substituted by a hydroxyl        group, or a benzyl group;    -   R_(b) and R′_(b), which are identical or different, each        represent a hydrogen atom, an aryl(C₁-C₄)alkyl group or a C₁-C₆        alkyl group which is optionally substituted; preferably R_(b)        and R′_(b) each represent a hydrogen atom or a C₁-C₃ alkyl or        benzyl group;    -   R_(c), R′_(c), R_(d) and R′_(d), which are identical or        different, each represent a hydrogen atom, an aryl(C₁-C₄)alkyl        group, C₁-C₆ alkoxy or a C₁-C₆ alkyl group which is optionally        substituted; R_(g), R′_(c), R_(d) and R′_(d) each represent        preferably a hydrogen atom, a hydroxyl, C₁-C₃ alkoxy, amino or        C₁-C₃ (di)alkylamino group or a C₁-C₃ alkyl group which is        optionally substituted by i) a hydroxyl group, ii) amino, iii)        C₁-C₃ (di)alkylamino, or iv) quaternary ammonium        (R″)(R′″)(R″″)N⁺; or two adjacent radicals R_(c) and R_(d) or        R′_(c) and R′_(d) which are carried by the same nitrogen atom        together form a heterocyclic or heteroaryl group; preferably the        heterocycle or heteroaryl is monocyclic and contains between 5        and 7 members; more preferably the groups are selected from        imidazolyl and pyrrolidinyl;    -   R_(e) and R′_(e), which are identical or different, each        represent a divalent, linear or branched, optionally unsaturated        C₁-C₆ alkylenyl hydrocarbon chain;    -   R_(f) and R′_(f), which are identical or different, each        represent a quaternary ammonium group (R″)(R′″)(R″″)N⁺— where        R″, R′″ and R″″, which are identical or different, each        represent a hydrogen atom or a C₁-C₄ alkyl group, or        (R″)(R′″)(R″″)⁺— represents an optionally substituted cationic        heteroaryl group, preferably an imidazolinium group which is        optionally substituted by a C₁-C₃ alkyl group;    -   R_(g), R′_(g), R″_(g), R′″_(g), R_(h), R′_(h), R″_(h) and        R′″_(h), which are identical or different, each represent a        hydrogen atom, a halogen atom, an amino, C₁-C₄ alkylamino, C₁-C₄        dialkylamino, cyano, carboxyl, hydroxyl or trifluoromethyl        group, an acylamino, C₁-C₄ alkoxy, C₂-C₄ (poly)hydroxyalkoxy,        alkylcarbonyloxy, alkoxycarbonyl or alkylcarbonylamino radical,        an acylamino, carbamoyl or alkylsulphonylamino radical, an        aminosulphonyl radical, or a C₁-C₁₆ alkyl radical optionally        substituted by a group selected from C₁-C₁₂ alkoxy, hydroxyl,        cyano, carboxyl, amino, C₁-C₄ alkylamino and C₁-C₄ dialkylamino,        or the two alkyl radicals carried by the nitrogen atom of the        amino group form a heterocycle containing 5 to 7 members and        optionally comprising another heteroatom which is identical to        or different from that of the nitrogen atom; preferably R_(g),        R′_(g), R″_(g), R′″_(g), R_(h), R′_(h), R″_(h) and R′″_(h)        represent a hydrogen or halogen atom or a C₁-C₃ alkyl group;    -   or two groups R_(g) and R′_(g); R″_(g) and R′″_(g); R_(h) and        R′_(h); or R″_(h) and R′″_(h), carried by two adjacent carbon        atoms, together form a benzo or indeno ring or a fused        heteroaryl or fused heterocycloalkyl group, the benzo, indeno,        heterocycloalkyl or heteroaryl ring being optionally substituted        by a halogen atom, an amino, C₁-C₄ alkylamino, C₁-C₄        dialkylamino, nitro, cyano, carboxyl, hydroxyl or        trifluoromethyl group, an acylamino, C₁-C₄ alkoxy, C₂-C₄        (poly)hydroxyalkoxy, alkylcarbonyloxy, alkoxycarbonyl, or        alkylcarbonylamino radical, an acylamino, carbamoyl or        alkylsulphonylamino radical, an aminosulphonyl radical, or a        C₁-C₁₆ alkyl radical which is optionally substituted by a group        selected from C₁-C₁₂ alkoxy, hydroxyl, cyano, carboxyl, amino,        C₁-C₄ alkylamino or C₁-C₄ dialkylamino, or the two alkyl        radicals carried by the nitrogen atom of the amino group form a        heterocycle containing 5 to 7 members and optionally containing        another heteroatom identical to or different from that of the        nitrogen atom; preferably R_(g) and R′_(g), and R″_(g) and        R′″_(g), together form a benzo group;    -   or, when G represents —NR_(c)R_(d) and G′ represents        —NR′_(c)R′_(d), two groups R_(c) and R′_(g); R′_(c) and R″_(g);        R_(d) and R_(g); or R′_(d) and R′″_(g) together form a saturated        heterocycle or heteroaryl which is optionally substituted by one        or more C₁-C₆ alkyl groups, preferably a heterocycle containing        one or two heteroatoms selected from nitrogen and oxygen and        containing between 5 and 7 members; more preferably the        heterocycle is selected from morpholinyl, piperazinyl,        piperidinyl and pyrrolidinyl groups;    -   R_(i), R′_(i), R″_(i), and R′″_(i) which are identical or        different, each represent a hydrogen atom or a C₁-C₄ alkyl        group;    -   R₁, R₂, R₃, R₄, R′₁, R′₂, R′₃ and R′₄, which are identical or        different, each represent a hydrogen atom or a C₁-C₄ alkyl,        C₁-C₁₂ alkoxy, hydroxyl, cyano, carboxyl, amino, C₁-C₄        alkylamino or C₁-C₄ dialkylamino group, it being possible for        said alkyl radicals to form, with the nitrogen atom which        carries them, a heterocycle containing 5 to 7 members that        optionally comprises another heteroatom which is different or        not different from the nitrogen; preferably R₁, R₂, R₃, R₄, R′₁,        R′₂, R′₃ and R′₄ are hydrogen atoms or an amino group; more        preferably R₁, R₂, R₃, R₄, R′₁, R′₂, R′₃ and R′₄ represent a        hydrogen atom;    -   T_(a) and T_(b), which are identical or different, represent i)        a covalent σ bond, ii) one or more radicals or combinations        thereof selected from —SO₂—, —O—, —S—, —N(R)—, —N⁺(R)(R^(o))—,        —CO—, with R and R^(o), which are identical or different,        representing a hydrogen atom or a C₁-C₄ alkyl or C₁-C₄        hydroxyalkyl radical, or an aryl(C₁-C₄)alkyl; preferably T_(a)        is identical to T_(b) and represents a covalent σ bond or a        group selected from —N(R)—, —C(O)—N(R)—, —N(R)—C(O)—, —O—C(O)—,        —C(O)—O— and —N⁺(R)(R^(o)—, where R and R^(o), which are        identical or different, each represent a hydrogen atom or a        C₁-C₄ alkyl group; more preferably T_(a) and T_(b) represent a σ        bond; iii) or a cationic or non-cationic heteroaryl or        heterocycloalkyl radical, which are preferably monocyclic,        preferably identical, and containing preferably two heteroatoms        (more preferably two nitrogen atoms) and containing preferably 5        to 7 members, such as imidazolium;

which are identical or different, each represent an optionallysubstituted heterocyclic group; preferably the heterocycles areidentical, monocyclic and saturated and contain a total of two nitrogenatoms and 5 to 8 members;

represents an aryl or heteroaryl group which is fused to the phenylring; or is absent from the phenyl ring; preferably, when the ring ispresent, the ring is a benzo;

-   -   m, m′, n and n′, which are identical or different, represent an        integer of between 0 and 6 inclusive, with m+n and m′+n′, which        are identical or different, each representing an integer between        1 and 10 inclusive; preferably m+n=m′+n′=an integer between 2        and 4 inclusive; more preferably m+n=m′+n′=an integer equal to        2;        M′ represents a counterion or an organic or inorganic acid salt.

Examples of fluorescent disulphide dyes include particularly thefollowing compounds:

where M′ is an anionic counterion.

I.5. The Organic Salt and Counterion:

An “organic or inorganic acid salt” is selected more particularly from asalt derived i) from hydrochloric acid HCl, ii) from hydrobromic acidHBr, iii) from sulphuric acid H₂SO₄, iv) from alkylsulphonic acids:Alk-S(O)₂OH such as methylsulphonic acid and ethylsulphonic acid; v)from arylsulphonic acids: Ar—S(O)₂OH such as benzenesulphonic acid andtoluenesulphonic acid; vi) from citric acid; vii) from succinic acid;viii) from tartaric acid; ix) from lactic acid, x) from alkoxysulphinicacids: Alk-O—S(O)OH such as methoxysulphinic acid and ethoxysulphinicacid; xi) from aryloxysulphinic acids such as tolueneoxysulphinic acidand phenoxysulphinic acid; xii) from phosphoric acid H₃PO₄; xiii) fromacetic acid CH₃COOH; xiv) from triflic acid CF₃SO₃H and xv) fromtetrafluoroboric acid HBF₄.

An “anionic counterion” is an anion or an anionic group which iscombined with the cationic charge of the dye; more particularly theanionic counterion is selected from i) halides such as chloride andbromide; ii) nitrates; iii) sulphonates, including C₁-C₆alkylsulphonates: Alk-S(O)₂O⁻ such as methylsulphonate or mesylate andethylsulphonate; iv) arylsulphonates: Ar—S(O)₂O⁻ such asbenzenesulphonate and toluenesulphonate or tosylate; v) citrate; vi)succinate; vii) tartrate; viii) lactate; ix) alkyl sulphites:Alk-O—S(O)O⁻ such as methylsulphite and ethyl sulphite; x) arylsulphites: Ar—O—S(O)O⁻ such as benzene sulphite and toluene sulphite;xi) alkyl sulphates: Alk-O—S(O)₂O⁻ such as methyl sulphate and ethylsulphate; xii) aryl sulphates: Ar—O—S(O)₂O⁻, xiii) phosphate; xiv)acetate; xv) triflate; and xvi) borates such as tetrafluoroborate.

I.6. Preparation of Fluorescent Disulphide Dyes:

The fluorescent disulphide dyes may be prepared by methods which areknown to a person skilled in the art.

According to a first possibility a disulphide compound containing twoamine functions, preferably primary or secondary amine functions, can bereacted with a sufficient amount of a “reactive fluorescent chromophore”or of a compound containing such a “reactive fluorescent chromophore”,in other words containing an electrophilic function.

“Reactive fluorescent chromophores” include reactive dyes containingmore particularly a vinyl sulphone, sulphatoethyl sulphone, mono- ordichlorotriazine, mono- or dichloropyrimidine, difluorochloropyrimidine,dichloroquinoxaline or bromovinyl sulphone function.

Also suitable as reactive chromophores are fluorescent chromophorecompounds containing at least one group which is capable of reactingwith an amine function to give a sulphamide (—SO₂—NR—) or amide(—CO—NR—) group. For example, mention may be made of the groups —SO₃W′and —COOW′ (where W′ represents a hydrogen atom, an alkali metal, suchas sodium or potassium, an ammonium group, an ammonium group which issubstituted by one or more identical or non-identical, linear orbranched, C₁-C₁₀ alkyl groups which optionally carry at least onehydroxyl), which may be activated beforehand, by known methods, to formrespectively an —SO₂Cl or —COCl group.

Consideration may also be given to employing, as the reactivefluorescent chromophore, the Colour Index acid dyes that are listed asbeing such.

Reference may be made more particularly to Advanced Organic Chemistry,March, 4th Edition, for further details on the operating conditionsemployed.

Still within the context of this first possibility, it is possible toemploy fluorescent chromophores comprising a labile group which isbonded directly or not to the fluorescent chromophore and can besubstituted by an amine group, such as Cl, Br, F, O-alkyl (for exampleO-Me), O-aryl, O-alkylaryl (for example O-benzyl).

In the context of this possibility, the fluorescent disulphide dyes mayalso be obtained by using chromophores possessing an acrylate function(—OOO—C═C—), on which an addition reaction is carried out.

In accordance with another possibility, the fluorescent disulphide dyesmay be obtained by reacting a disulphide compound with a compound whichcarries two carboxylic acid functions which are activated byconventional methods (for example, reaction with a carbodiimide or withthionyl chloride). The resulting product is then reacted with afluorescent chromophore which carries a nucleophilic function, ofprimary or secondary amine type for example, or of aliphatic or aromaticalcohol type such as phenol.

Here again, reference may be made to Advanced Organic Chemistry, March,4th Edition, for further details on the operating conditions employed.

In accordance with a third possibility, the fluorescent disulphide dyesmay be obtained by reacting a compound containing a disulphide group andtwo hydroxyl groups which are activated beforehand to form leavinggroups (for example mesylate or tosylate) with a fluorescent chromophorewhich carries a nucleophilic function, advantageously of primary,secondary or tertiary, heteroaromatic or non-heteroaromatic type, forexample of pyridine, imidazole or benzimidazole type.

In accordance with a fourth possibility, the fluorescent disulphide dyesmay be obtained by controlled oxidation of dyes which carry an SHfunction.

In accordance with a fifth possibility, and particularly for thepreparation of compounds corresponding to the formula (II), thefluorescent disulphide dyes may be obtained by a variant ofpossibilities one, two or three described above, by using a molarquantity of disulphide reagent that is greater than or equal to themolar quantity of reagent containing the chromophore group.

The preparation of fluorescent disulphide dyes corresponding to theformula (I) for which A and A′ are identical is made easier, on theother hand, by the use of a molar quantity of reagent containing thefluorescent chromophore group that is preferably greater than or equalto two times the amount of disulphide reagents.

In accordance with a sixth possibility, and particularly for thepreparation of compounds corresponding to the formula (I) in which thetwo groups A and A′ on the one hand and X and X′ on the other hand aredifferent, the disulphide compounds may be obtained from fluorescentdisulphide compounds corresponding to the formula (II).

II. Dyeing Composition:

II.1. Dyes:

The dyeing composition used in the invention generally contains anamount of fluorescent disulphide dye of between 0.001% and 50% relativeto the total weight of the composition. Preferably this amount isbetween 0.005% and 20% by weight and more preferably still between 0.01%and 5% by weight relative to the total weight of the composition.

The dyeing composition may further comprise additional direct dyes.These direct dyes are selected for example from neutral, acidic orcationic nitrobenzene direct dyes, neutral, acidic or cationic azodirect dyes, tetraazapentamethine dyes, quinone dyes and moreparticularly neutral, acidic or cationic anthraquinone dyes, azinedirect dyes, triarylmethane direct dyes, indoamine direct dyes andnatural direct dyes.

The natural direct dyes include lawsone, juglone, alizarin, purpurin,carminic acid, kermesic acid, purpurogallin, protocatechaldehyde,indigo, isatin, curcumin, spinulosin and apigenidin. It is also possibleto use extracts or decoctions containing these natural dyes, and moreparticularly henna-base poultices or extracts.

The dyeing composition may contain one or more oxidation bases and/orone or more couplers that are conventionally used for the dyeing ofkeratin fibres.

The oxidation bases include para-phenylenediamines,bisphenylalkylene-diamines, para-aminophenols, bis-para-aminophenols,ortho-aminophenols, hetero-cyclic bases and their addition salts.

These couplers may include, more particularly, meta-phenylenediamines,meta-aminophenols, meta-diphenols, naphthalene couplers, heterocycliccouplers and their additional salts.

The coupler or couplers are each generally present in an amount ofbetween 0.001% and 10% by weight of the total weight of the dyeingcomposition, preferably between 0.005% and 6%.

The oxidation base or bases which are present in the dyeing compositionare generally each present in an amount of between 0.001% to 10% byweight of the total weight of the dyeing composition, preferably between0.005% and 6% by weight.

Generally speaking, the addition salts of the oxidation bases and of thecouplers than can be used in the context of the invention are selectedmore particularly from the addition salts with an acid, such ashydrochlorides, hydrobromides, sulphates, citrates, succinates,tartrates, lactates, tosylates, benzenesulphonates, phosphates andacetates, and the addition salts with a base, such as alkali metalhydroxides, for instance sodium hydroxide and potassium hydroxide,aqueous ammonia, amines or alkanolamines.

The medium appropriate for dyeing, also referred to as a dyeing vehicle,is a cosmetic medium which is generally composed of water or of amixture of water and at least one organic solvent. Organic solventsinclude, for example, C₁-C₄ lower alkanols, such as ethanol andisopropanol; polyols and polyol ethers such as 2-butoxyethanol,propylene glycol, propylene glycol monomethyl ether, diethylene glycolmonoethyl ether and monomethyl ether, and also aromatic alcohols such asbenzyl alcohol or phenoxyethanol, and mixtures thereof.

The solvents, when present, are present preferably in proportions ofpreferably between 1% and 40% by weight, approximately, relative to thetotal weight of the dyeing composition, and more preferably stillbetween 5% and 30% by weight, approximately.

In one variant the invention contains a reducing agent which is capableof reducing the disulphide bonds. This reducing agent is as definedabove.

II.2. Adjuvants:

The dyeing composition may also include various adjuvants which areconventionally used in hair dyeing compositions, such as anionic,cationic, nonionic, amphoteric and zwitterionic surfactants or mixturesthereof, anionic, cationic, nonionic, amphoteric and zwitterionicpolymers or mixtures thereof, organic or inorganic thickeners, andespecially anionic, cationic, nonionic and amphoteric polymericassociative thickeners, antioxidants, penetrants, sequestrants,fragrances, buffers, dispersants, conditioning agents such as, forexample, volatile or non-volatile, modified or non-modified silicones,such as amino silicones, film formers, ceramides, preservatives,opacifiers and conductive polymers.

Amount of Adjuvants:

The adjuvants above are generally present in an amount, for each ofthem, of between 0.01% and 20% by weight relative to the weight of thecomposition.

A person skilled in the art would of course take care to select this orthese complementary compounds in such a way that the advantageousproperties intrinsically attaching to the dyeing composition inaccordance with the invention are not, or not substantially, adverselyaffected by the intended addition or additions.

pH

The pH of the dyeing composition is generally between 3 and 14approximately, and preferably between 5 and 11 approximately. It may beadjusted to the desired value by means of acidifying or alkalifyingagents which are commonly used in the dyeing of keratin fibres or elseby means of conventional buffer systems.

Acidifying agents include, for example, organic or inorganic acids suchas hydrochloric acid, orthophosphoric acid, sulphuric acid, carboxylicacids such as acetic acid, tartaric acid, citric acid and lactic acid,and sulphonic acids. Alkalifying agents include, for example, aqueousammonia, alkali metal carbonates, alkanolamines such as mono-, di- andtriethanolamines and their derivatives, sodium hydroxide or potassiumhydroxide, and the compounds of formula

in which W_(a) is a propylene residue which is optionally substituted bya hydroxyl group or a C₁-C₄ alkyl radical, and R_(a1), R_(a2), R_(a3)and R_(a4), which are identical or different, each represent a hydrogenatom or a C₁-C₄ alkyl or C₁-C₄ hydroxyalkyl radical.

II.3. Forms of the Composition:

The dyeing composition may be presented in various forms, such as in theform of a liquid, cream or gel, or in any other form which isappropriate for performing the dyeing of keratin fibres, and moreparticularly of the hair.

III. Colouring Method:

The dyeing composition is generally applied at ambient temperature. Itmay, however, be carried out at temperatures ranging from 20 to 180° C.

In one particular colouring method of the invention, the fluorescentdisulphide dye is applied to the keratin materials at the same time as areducing agent. The reducing agent is as defined above.

In another variant, the reducing agent is added to the dyeingcomposition containing the fluorescent disulphide dyes (I) and (II) atthe time of use.

In accordance with another variant, the method of the invention may beimplemented in the presence of a post-treatment oxidizing agent when thecomposition already contains a reducing agent.

The oxidizing agent may be any oxidizing agent which is conventionallyused in the art. Hence it may be selected from hydrogen peroxide, ureaperoxide, alkali metal bromates, persalts such as perborates andpersulphates, and also enzymes, among which mention may be made ofperoxidases, 2-electron oxidoreductases such as uricases, and 4-electronoxygenases such as laccases. The use of hydrogen peroxide isparticularly preferred.

This oxidizing agent may be applied to the fibres before or after theapplication of the composition containing the fluorescent disulphidedyes of formulae (I) and (II).

IV. Dyeing Device or Kit.

The invention further provides a multi-compartment dyeing device or kit,in which a first compartment contains a dyeing composition comprising atleast one fluorescent disulphide dye of formulae (I) or (II) and asecond compartment contains a reducing agent capable of reducing thedisulphide bond of the dye and/or the disulphide functions of thekeratin materials.

One of these compartments may further contain one or more other dyes ofdirect dye or oxidation dye type.

The invention further pertains to a multi-compartment device in which afirst compartment contains a dyeing composition comprising at least onefluorescent disulphide dye of formulae (I) or (II), a second compartmentcontains a reducing agent capable of reducing the disulphide bond of thedye, and a third compartment contains an oxidizing agent.

Each of the aforementioned devices may be equipped with means allowingthe desired mixture to be delivered to the hair, such as, for example,the devices described in patent FR2 586 913.

The examples which follow serve to illustrate the invention, but withoutexhibiting any limitative nature. The fluorescent disulphide dyes in theexamples below were entirely characterized by conventional spectrometricand spectroscopic methods.

EXAMPLES Synthesis Examples Example 1

Step 1:1,1′-(Disulphanediyldiethane-2,1-diyl)bis(2-methylpyridinium)dibromide

A mixture of 56 g of 1-bromo-2-[(2-bromoethyl)disulphanyl]ethane and 15ml of N-methylpyrrolidone (NMP) is introduced dropwise into 35 g of2-picoline with stirring at 80° C. The mixture (white suspension) iskept with stirring at 80° C. for 30 minutes, 100 ml of acetonitrile areadded, and stirring is maintained at 80° C. for 90 minutes. Aftercooling, the solid obtained is filtered off, washed with 100 ml ofacetonitrile and then dried.

This gives 56.2 g of brown powder. 45 g of this powder are suspended in300 ml of isopropanol at reflux. When the temperature has dropped to 40°C., the solid is filtered off, washed with 3 times 100 ml of isopropanoland dried under vacuum. Light beige product, 40.56 g. Analyses inaccordance with the anticipated structure.

Step 2:1,1′-(Disulphanediyldiethane-2,1-diyl)bis(2-{(E)-2-[4-(dimethylamino)-phenyl]vinyl}pyridinium)dibromide

150 mg of pyrrolidine and then 129 mg of acetic acid are added to asolution of 297 mg of 4-dimethylaminobenzaldehyde in 2 ml of methanol.

After 18 h of stirring at ambient temperature, 495 mg of1,1′-(disulphanediyldiethane-2,1-diyl)bis(2-methylpyridinium)dibromideare added to the mixture, and stirring is maintained at ambienttemperature for 7 days. Following filtration, washing with methanol anddrying under vacuum, 312 mg of orange powder are recovered. Analyses inaccordance with the anticipated structure. ¹H NMR (400 MHz, MeOH-d₄):3.02 (s, 6H), 3.22 (t, 2H), 5 (t, 2H), 6.72 (m, 2H), 7.19 (d, 1H), 7.63(m, 3H), 7.76 (d, 1H), 8.3 (m, 2H), 8.59 (m, 1H).

Example 2

Step 1:4,4′-{Disulphanediylbis[ethane-2,1-diyl(methylimino)]}dibenzaldehyde

82.3 g of phosphorus oxychloride are added to 500 ml of DMF at 0° C.After 30 minutes of stirring at 0° C., a solution of 47 g ofN,N′-(disulphanediyldiethane-2,1-diyl)bis(N-methylaniline) is addeddropwise. The mixture is stirred at 0° C. for 90 minutes and then at 10°C. for 75 minutes and at 40° C. for 105 minutes. It is then poured into2.5 l of ice-water, and 700 ml of 5N sodium hydroxide are added. Theyellow precipitate obtained is filtered off on celite and dissolved in200 ml of dichloromethane and the resulting solution is washed with 200ml of saturated aqueous sodium chloride solution. After drying overmagnesium sulphate and evaporation of the dichloromethane, the yellowresidue (80 g) is purified by chromatography on silica gel.

After drying, a light yellow powder is recovered. The analyses indicatethat the product is in accordance with the expected structure.

Step 2:2,2′-{Disulphanediylbis[ethane-2,1-diyl(methylimino)-4,1-phenylene(E)-ethene-2,1-diyl]}bis(1-methylpyridinium)dichloride

25 g of4,4′-{disulphanediylbis[ethane-2,1-diyl(methylimino)]}dibenzaldehyde and18.5 g of N-methylpicolinium chloride are dissolved in 300 ml ofmethanol. 12.7 ml of piperidine are added to the mixture. The combinedsystem is heated with stirring at 55° C. for 11 hours. The methanol isremoved under vacuum at 40° C. The solid is mixed with 300 ml ofisopropanol. Following renewed drying by evaporation, 200 ml ofisopropanol are introduced. The mixture solidifies, and is extended byadding 100 ml of isopropanol and filtered off with suction on a glassfrit. The solid recovered is washed with isopropanol and then withacetone and then dried under vacuum. After drying, 36.7 g of orangepowder are recovered. By recrystallization from isopropanol, 27 g ofhigh-purity orange-red powder are recovered. The analyses indicate thatthe product is in accordance with specification and is pure. ¹H NMR (400MHz, MeOH-d₄) 2.99 (t, 4H), 3.81 (t, 4H), 4.31 (s, 6H), 6.86 (d, 4H),7.22 (d, 2H), 7.63 (m, 2H), 7.69 (d, 4H), 7.83 (d, 2H), 8.29 (m, 2H),8.36 (m, 2H), 8.61 (m, 2H).

Example 3

4,4′-{Disulphanediylbis[ethane-2,1-diyl(methylimino)-4,1-phenylene(E)ethene-2,1-diyl]}bis(1-methylpyridinium)dimethoxysulphate

2.62 g of 4-picoline are diluted in 25 ml of dichloromethane, and 3 mlof dimethyl sulphate are added to this solution, whose temperature risesto reflux (40° C.). After 40 minutes of stirring, 50 ml of isopropanolare added, and the mixture is concentrated by distillation of thedichloromethane (mixture heated at 60° C.). 1.83 g of pyrrolidine areintroduced into the mixture, followed by 4.99 g of4,4′-{disulphanediylbis[ethane-2,1-diyl(methylimino)]}dibenzaldehyde.After 2 hours of stirring at 65° C., the reaction mixture is cooled toambient temperature and the precipitate formed is filtered off andwashed with 3 times 100 ml of isopropanol. The red paste obtained isdispersed in 200 ml of isopropanol, and the mixture thus obtained isheated to reflux and then cooled. The red precipitate formed is filteredoff and then dried. 8.94 g of red powder are recovered. The analysesindicate that the product is in accordance with specification and pure.¹H NMR (400 MHz, DMSO-d₆) 2.96 (t, 4H), 3.02 (s, 6H), 3.36 (s, 6H), 3.72(t, 4H), 4.16 (s, 6H), 6.81 (d, 4H), 7.15 (d, 2H), 7.57 (d, 4H), 7.87(d, 2H), 8.02 (d, 4H), 8.66 (d, 4H).

Example 42,2′-{Disulphanediylbis[ethane-2,1-diyl(methylimino)-4,1-phenylene(E)ethene-2,1-diyl]}bis(1-ethylpyridinium)dichloride

10 g of4,4′-{disulphanediylbis[ethane-2,1-diyl(methylimino)]}dibenzaldehyde and8.1 g of N-ethylpicolinium chloride are dissolved in 100 ml ofisopropanol. 1.3 g of piperidine are added to the mixture. The combinedsystem is heated with stirring at reflux for 5 hours. The isopropanol isremoved under vacuum at 50° C. The gum obtained is triturated withacetone. 18 g of solid are recovered and are treated with carbon black.7.1 g of product are collected, and 4 g are purified by liquid/liquid(water/BuOH) chromatography. After drying, 1.65 g of red powder arerecovered. The analyses indicate that the product is in accordance withspecification and pure. ¹H NMR (400 MHz, MeOH-d₄) 1.57 (t, 6H), 2.98 (t,4H), 3.11 (s, 6H), 3.8 (t, 4H), 4.73 (q, 4H), 6.85 (m, 4H), 7.23 (d,2H), 7.69 (m, 6H), 7.85 (d, 2H), 8.29 (m, 2H), 8.38 (m, 2H), 8.67 (m,2H).

Example 5 Step 1:2,2′-(Disulphanediyldiethane-2,1-diyl)bis(6-chloro-1H-benzo[de]-isoquinoline-1,3(2H)-dione)

9.30 g of 6-chloro-1H,3H-benzo[de]isochromene-1,3-dione and 4.46 g ofhydrochlorided cystamine hydrochloride are suspended in 50 ml ofN-methylpyrrolidone (NMP). 5.5 g of diisopropylethylamine are added andthe mixture is heated with stirring at 120° C. After two hours, 50 ml ofNMP are added and the mixture is kept with stirring at 120° C. for 3hours. After cooling, the precipitated product is recovered and thefiltered solution is extended by addition of 200 ml of water, and asecond precipitate is recovered. The precipitates are washed with waterand dried. 11.46 g of white powder are recovered. The analyses show thatthe product is in accordance with the expected product.

Step 2:2,2′-(Disulphanediyldiethane-2,1-diyl)bis[6-{[3-(dimethylamino)propyl]-amino}-1H-benzo[de]isoquinoline-1,3(2H)-dione]

4 g of(6-chloro-2-(2-{[2-(6-chloro-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)ethyl]-disulphanyl}ethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dioneare suspended in 40 ml of N,N-dimethylpropane-1,3-diamine. The mixtureis heated with stirring at 110° C. for 12 hours. After cooling, a yellowprecipitate is collected, and 500 ml of a 1/1 ethanol/water mixture areadded dropwise to the filtrate. The yellow paste obtained is isolatedand triturated with 200 ml of acetone. The solids obtained are washedwith 300 ml of water and dried. 4.5 g of yellow powder are recovered.The analyses show that the product is in accordance with the expectedproduct.

Step 3:3,3′-{Disulphanediylbis[ethane-2,1-diyl(1,3-dioxo-1H-benzo[de]iso-quinoline-2,6(3H)-diyl)imino]}bis(N,N,N-trimethylpropan-1-aminium)sulphate

4 g of6-{[3-(dimethylamino)propyl]amino}-2-[2-({2-[6-{[3-(dimethylamino)propyl]-amino}-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl]ethyl}disulphanyl)ethyl]-1H-benzo-[de]isoquinoline-1,3(2H)-dioneare suspended in 50 ml of dimethylformamide. 4 ml of dimethyl sulphateare added and the mixture is kept with stirring at ambient temperaturefor 4 hours. The reaction mixture is poured into 500 ml of ethylacetate. The precipitate is filtered off, washed with 4 times 100 ml ofethyl acetate and dried under vacuum. This gives 5.9 g of yellow powder.The analyses indicate that the product is in accordance with theexpected product. ¹H NMR (400 MHz, DMSO-d₆): 2.13 (m, 4H), 3.06 (m, 4H),3.09 (s, 18H), 3.46 (m, 4H), 4.36 (m, 4H), 6.85 (d, 2H), 7.71 (m, 2H),7.82 (t, 2H), 8.28 (d, 2H), 8.29 (dd, 2H), 8.45 (dd, 2H).

Example 6

Step 1:1,1′-(Disulphanediyldiethane-2,1-diyl)bis(4-methylpyridinium)dibromide

67 g of 4-picoline are diluted in 100 ml of acetonitrile and the mixtureis heated to 80° C. A mixture of 60 g of1-bromo-2-[(2-bromoethyl)disulphanyl]ethane and 15 ml ofN-methylpyrrolidone (NMP) is added over 5 minutes. After 4 hours ofstirring at 85° C., the mixture is cooled. The solid obtained isfiltered off, rinsed with 3×200 ml of acetonitrile and then dissolved in800 ml of isopropanol (at reflux). After cooling, 1 l of ethyl ether isadded. The precipitate formed is filtered off, rinsed with 3×200 ml ofethyl ether and then dried. The off-white powder obtained (73.77 g)contains a great majority (>90%) of the expected product, which is usedas it is for the following step.

Step 2:1,1′-(Disulphanediyldiethane-2,1-diyl)bis(4-{(E)-2-[4-(dimethylamino)-phenyl]vinyl}pyridinium)dibromide

13.2 g of 4-dimethylaminobenzaldehyde are suspended in 100 ml ofmethanol. 6.2 g of pyrrolidine and then 5.3 g of acetic acid, diluted in20 ml of methanol, are added to the mixture (final pH ⅚). 20 g of1,1′-(disulphanediyldiethane-2,1-diyl)bis(4-methyl-pyridinium)dibromide, obtained in the preceding step, and dissolved in 80 ml ofmethanol, are introduced, and then the reaction mixture is diluted byaddition of 100 ml of methanol. After 21 h of stirring at ambienttemperature, a first precipitate is recovered, washed with 3×100 ml ofethanol and then 3×200 ml of ethyl acetate and dried (red powder, 7.4g), and then a second precipitate, formed in the filtrate, is likewiserecovered and dried (red powder, 11.44 g). The analyses indicate thatthe two fractions are in accordance with the structure expected. ¹H NMR(400 MHz, MeOH-d₄): 3.02 (s, 12H), 3.42 (t, 4H), 4.74 (t, 4H), 6.77 (d,4H), 7.19 (d, 2H), 7.6 (d, 4H), 7.97 (d, 2H), 8.1 (d, 4H), 8.79 (d, 4H).

Example 7

Synthesis Scheme

Step 1: Synthesis ofN,N′-(disulphanediyldiethane-2,1-diyl)bis(2-chloroacetamide)

40.3 g of cystamine dihydrochloride are dissolved in 100 ml of water, 32ml of 35% sodium hydroxide solution are added (pH 9.7) and thetemperature is lowered to 5° C. 33.5 ml of chloracetyl chloride areintroduced dropwise, with the temperature being maintained at less than10° C. and the pH at between 7.9 and 9.3 by addition of sodium hydroxidesolution. The mixture is maintained with stirring at ambient temperaturefor 2 hours. The precipitate is filtered off, washed with 5×150 ml ofwater and then dried under vacuum in the presence of P₂O₅. 35.3 g ofwhite powder are recovered. The analyses indicate that the productconforms.

Step 2: Synthesis of1,1′-{disulphanediylbis[ethane-2,1-diylimino(2-oxoethane-2,1-diyl)]}bis(4-methylpyridinium)dichloride

6.1 g of N,N′-(disulphanediyldiethane-2,1-diyl)bis(2-chloroacetamide)and 4.5 g of 4-picoline are dissolved in 50 ml of NMP and the solutionis heated at 80° C. for 19 hours. After the mixture has been cooled, 9.2g of salts are recovered by successive precipitations from acetone anddrying under vacuum. The analyses show that the product conforms. ¹H NMR(400 MHz, D₂O): 2.61 (s, 6H), 2.82 (t, 4H), 3.56 (t, 4H), 5.31 (s, 4H),7.85 (d, 4H), 8.51 (d, 4H).

Step 3: Synthesis of1,1′-{disulphanediylbis[ethane-2,1-diylimino(2-oxoethane-2,1-diyl)]}bis{4-[(E)-2-(3,4,5-trimethoxyphenyl)vinyl]pyridinium}dichloride[4]

785 mg of 3,4,5-trimethoxybenzaldehyde, 328 μl of pyrrolidine, 232 μl ofacetic acid and 490 mg of1,1′-{disulphanediylbis[ethane-2,1-diylimino(2-oxoethane-2,1-diyl)]}bis-(4-methylpyridinium)dichlorideare dissolved in 10 ml of isopropanol and the solution is kept withstirring at ambient temperature for 3 hours 30 minutes. The mixture ispoured into 50 ml of a 1:1 dichloromethane/acetone solution. A solidprecipitates. It is filtered off, washed with three times 20 ml ofacetone and dried under vacuum. 509 mg of black powder are recovered.The analyses show that the product conforms (LCMS: 100%; mass peakm/z=388, corresponding to the dication).

Colouring Examples Preparation of a Composition A

Disulphide dye of formula (I) of the invention 10⁻³ mol % Benzyl alcohol4 g Polyethylene glycol 6OE 6 g Hydroxyethylcellulose 0.7 gAlkylpolyglucoside in aqueous solution 4.5 g containing 65% activesubstance Demineralized water qs 100 g

Preparation of a composition B

Thioglycolic acid 1M Sodium hydroxide qs pH 8.5 Demineralized water qs100 gAt the time of use, the compositions A (9 volumes) and B (1 volume) aremixed and the resulting mixture is then applied to dark hair (tone level4) for 30 minutes at ambient temperature. After rinsing with water anddrying, optical lightening of the hair thus treated is observed.

The locks thus treated are subjected to 30 shampooings in a cycle whichcomprises the wetting of the locks with water, washing with shampoos,rinsing with water, and then drying.

The lock is dried before the next shampoo is applied.

The colour of the locks before and after 30 washes was evaluated in theL*a*b* system by means of a MINOLTA® CM 2002 spectrophotometer (D65illuminant).

In the L*a*b* system, the three parameters denote respectively theintensity (L*), the hue (a*) and the saturation (b*). In this system,the higher the value of L, the lighter or less intense the colour,Conversely, the lower the value of L, the darker or greater degree ofintensity of the colour a* and b* indicate two colour axes: a* indicatesthe green/red colour axis, and b* the blue/yellow colour axis.

L a* b* Compound 1 24.85 8.08 7.68 Compound 1 after 30 24.78 7.83 7.56shampooings Compound 2 26.32 6.38 10.01 Compound 2 after 30 25.61 5.489.05 shampooings Compound 3 25.49 10.56 9.96 Compound 3 after 30 25.9811.41 9.86 shampooings Compound 4 25.87 6.06 9.60 Compound 4 after 3024.38 5.86 9.20 shampooings Compound 5 25.08 1.19 7.51 Compound 5 after30 25.72 1.38 6.01 shampooingsThe results in the table above show that the colouring changes verylittle even after 30 shampooings. Thus the colouring and the lighteningeffect on the hair remains virtually unchanged, hence indicating verygood shampooing resistance on the part of the dyes of the invention.

1. A method of coloring dark keratin fibers, possessing a tone level ofless than or equal to 6, comprising applying to said dark keratin fibersa dyeing composition comprising, in an appropriate cosmetic medium, atleast one fluorescent disulphide entity and simultaneously applying tothe dark keratin fibers at least one reducing agent, wherein the atleast one fluorescent disulphide entity is selected from the entities offormula (I):A-(X)_(p)—C_(sat)—S—S—C′_(sat)—(X′)_(p)-A′  (I) the organic andinorganic acid salts, optical isomers and geometrical isomers, and thesolvates thereof; wherein: A and A′, which are identical, each representa radical containing at least one cationic fluorescent chromophore; Xand X′, which are identical or different, each represent a saturated orunsaturated, linear or branched C₁-C₃₀ hydrocarbon chain which isoptionally interrupted and/or optionally terminated at one or two of itsends by at least one divalent group selected from: —N(R)—, —N⁺(R)(R)—,—O—, —S—, —CO—, and —SO₂—, wherein radicals R, which are identical ordifferent, are each selected from hydrogen or C₁-C₄ alkyl, hydroxyalkyland aminoalkyl radicals; and saturated or unsaturated, fused ornon-fused, aromatic or non-aromatic (hetero)cyclic radicals optionallycomprising at least one identical or non-identical heteroatom andoptionally substituted; p and p′, which are identical or different, areeach 0 or 1; and —C_(sat) and C′_(sat), which are identical ordifferent, each represent an optionally cyclic, optionally substituted,linear or branched C₁-C₁₈ alkylene chains.
 2. The method according toclaim 1, wherein X and X′, which are identical or different, represent agroup —N(R)—, wherein the radicals R, which are identical or different,are selected from hydrogen or C₁-C₄ alkyl, hydroxyalkyl and aminoalkylradicals.
 3. The method according to claim 1, wherein A and A′, whichare identical, represent W—C(R^(c))═C(R^(d))—Ar— or—W—C(R^(c))═C(R^(d))—Ar, and further wherein W represents a heterocycleor a heteroaryl containing a quaternary ammonium; Ar represents a 5- or6-membered (hetero)aryl radical of phenyl or pyridinium type, or a(hetero)aromatic bicyclic radical of naphthyl, benzopyridinium,indolinyl or benzoindolinyl type, optionally substituted by at least onehalogen atom, alkyl group, hydroxyl group, alkoxy group, hydroxyalkylgroup, amino or (di)alkylamino group, acylamino group; or one 5- or6-membered heteroaryl or heterocycloalkyl group; and R^(c) and R^(d),which are identical or different, each represent a hydrogen atom or aC₁-C₄ alkyl group.
 4. The method according to claim 3, wherein W ischosen from imidazolium, pyridinium, benzopyridinium, benzimidazolium,quinolinium and pyrazolium.
 5. The method according to claim 1, whereinthe at least one fluorescent disulphide entity is selected fromcompounds of formula (VI):

wherein R_(b) and R′_(b), which are identical or different, eachrepresent a hydrogen atom, an aryl(C₁-C₄)alkyl group or a C₁-C₆ alkylgroup which is optionally substituted; R_(e) and R′_(e), which areidentical or different, each represent a divalent, linear or branched,optionally unsaturated C₁-C₆ alkylenyl hydrocarbon chain; R_(f) andR′_(f), which are identical or different, each represent a quaternaryammonium group (R″)(R′″)(R″″)N⁺ wherein R″, R′″ and R″″, which areidentical or different, each represent a hydrogen atom or a C₁-C₄ alkylgroup, or (R″)(R′″)(R″″)N⁺— represents an optionally substitutedcationic heteroaryl group, which is optionally substituted by a C₁-C₃alkyl group; R_(g), R′_(g), which are identical or different, eachrepresent a hydrogen atom, a halogen atom, an amino, C₁-C₄ alkylamino,C₁-C₄ dialkylamino, cyano, carboxyl, hydroxyl or trifluoromethyl group,an acylamino, C₁-C₄ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, alkylcarbonyloxy,alkoxycarbonyl or alkylcarbonylamino radical, an acylamino, carbamoyl oralkylsulphonylamino radical, an aminosulphonyl radical, or a C₁-C₁₆alkyl radical optionally substituted by a group selected from C₁-C₁₂alkoxy, hydroxyl, cyano, carboxyl, amino, C₁-C₄ alkylamino and C₁-C₄dialkylamino, or the two alkyl radicals carried by the nitrogen atom ofthe amino group form a heterocycle containing 5 to 7 members andoptionally comprising another heteroatom which is identical to ordifferent from that of the nitrogen atom; or two groups R_(g) andR′_(g); carried by two adjacent carbon atoms, together form a benzo orindeno ring or a fused heteroaryl or fused heterocycloalkyl group, thebenzo, indeno, heterocycloalkyl or heteroaryl ring being optionallysubstituted by a halogen atom, an amino, C₁-C₄ alkylamino, C₄dialkylamino, nitro, cyano, carboxyl, hydroxyl or trifluoromethyl group,an acylamino, C₁-C₄ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, alkylcarbonyloxy,alkoxycarbonyl, or alkylcarbonylamino radical, an acylamino, carbamoylor alkylsulphonylamino radical, an aminosulphonyl radical, or a C₁-C₁₆alkyl radical which is optionally substituted by a group selected fromC₁-C₁₂ alkoxy, hydroxyl, cyano, carboxyl, amino, C₁-C₄ alkylamino andC₁-C₄ dialkylamino; or the two alkyl radicals carried by the nitrogenatom of the amino group form a heterocycle containing 5 to 7 members andoptionally comprising another heteroatom identical to or different fromthat of the nitrogen atom; —R₁, R₂, R₃, R₄, R′₁, R′₂, R′₃ and R′₄, whichare identical or different, each represent a hydrogen atom or a C₁-C₄alkyl, C₁-C₁₂ alkoxy, hydroxyl, cyano, carboxyl, amino, C₁-C₄ alkylaminoor C₁-C₄ dialkylamino group, it being possible for said alkyl radicalsto form, with the nitrogen atom which carries them, a heterocyclecontaining 5 to 7 members, optionally comprising another heteroatomdifferent or not different from nitrogen; T_(a) and T_(b), which areidentical or different, represent: i) a covalent a bond; ii) at leastone radical selected from —SO₂—, —O—, —S—, —N⁺(R)(R^(o))—, and —CO—;wherein R and R^(o), which are identical or different, represent ahydrogen atom or a C₁-C₄ alkyl or C₁-C₄ hydroxyalkyl radical, or anaryl(C₁-C₄)alkyl; or iii) a cationic or non-cationic heteroaryl orheterocycloalkyl radical; m, m′, n and n′, which are identical ordifferent, represent an integer ranging from 0 to 6, wherein m+n andm′+n′, and which are identical or different, each represents an integerranging from 1 to 10; and M′ represents a counterion or an organic orinorganic acid salt.
 6. The method according to claim 5, wherein atleast one of R_(f) or R′_(f) represents an imidazolinium group.
 7. Themethod according to claim 1, wherein the at least one fluorescentdisulphide entity is selected from:

wherein M′ is an anionic counterion.
 8. The method according to claim 1,wherein the at least one reducing agent is selected from: cysteine,homocysteine, thiolactic acid, and salts thereof; phosphines;bisulphite; sulphites; and thioglycolic acid and esters of thioglycolicacid.
 9. The method according to claim 1, wherein the dark keratinfibers possess a tone level of less than or equal to
 4. 10. The methodaccording to claim 1, further comprising applying at least one oxidizingagent to the keratin fibers.
 11. The method according to claim 1,wherein the at least one fluorescent disulphide entity is present in anamount ranging from 0.001% to 50% by weight, relative to the totalweight of the dyeing composition.
 12. The method according to claim 11,wherein the at least one fluorescent disulphide entity is present in anamount ranging from 0.005% to 20% by weight, relative to the totalweight of the dyeing composition.
 13. The method according to claim 12,wherein the at least one fluorescent disulphide entity is present in anamount ranging from 0.01% to 5% by weight, relative to the total weightof the dyeing composition.
 14. A multicompartment device comprising atleast one first compartment comprising a dyeing composition for darkkeratin fibers possessing a tone level of less than or equal to 6,comprising at least one fluorescent disulphide entity chosen fromformula (I):A-(X)_(p)—C_(sat)—S—S—C′_(sat)—(X′)_(p)-A  (I) the organic and inorganicacid salts, optical isomers and geometrical isomers, and the solvatesthereof; wherein: A and A′, which are identical, each represents aradical containing at least one cationic fluorescent chromophore; X andX′, which are identical or different, each represent a saturated orunsaturated, linear or branched C₁-C₃₀ hydrocarbon chain which isoptionally interrupted and/or optionally terminated at one or two of itsends by at least one divalent group selected from: —N(R)—, —N⁺(R)(R)—,—O—, —S—, —CO—, and —SO₂—, wherein radicals R, which are identical ordifferent, are each selected from hydrogen or C₁-C₄ alkyl, hydroxyalkyland aminoalkyl radicals; and saturated or unsaturated, fused ornon-fused, aromatic or non-aromatic (hetero)cyclic radicals optionallycomprising at least one identical or non-identical heteroatom andoptionally substituted; p and p′, which are identical or different, areeach 0 or 1; —C_(sat) and C′_(sat), which are identical or different,each represent an optionally cyclic, optionally substituted, linear orbranched C₁-C₁₈ alkylene chains; and at least one second compartmentcomprising at least one reducing agent.
 15. A method of lightening darkkeratin fibers possessing a tone level of less than or equal to 6,comprising applying to said dark keratin fibers a dyeing compositioncomprising, in an appropriate cosmetic medium, at least one fluorescentdisulphide entity and simultaneously applying to said dark keratinfibers at least one reducing agent, wherein the at least one fluorescentdisulphide entity is selected from the entities of formula (I) and:A-(X)_(p)—C_(sat)—S—S—C′_(sat)—(X′)_(p′)-A′  (I) the organic andinorganic acid salts, optical isomers and geometrical isomers, and thesolvates thereof; wherein: A and A′, which are identical, eachrepresents a radical containing at least one cationic fluorescentchromophore; X and X′, which are identical or different, each representa saturated or unsaturated, linear or branched C₁-C₃₀ hydrocarbon chainwhich is optionally interrupted and/or optionally terminated at one ortwo of its ends by at least one divalent group selected from: —N(R)—,—N⁺(R)(R)—, —O—, —S—, —CO—, and —SO₂—, wherein radicals R, which areidentical or different, are each selected from hydrogen or C₁-C₄ alkyl,hydroxyalkyl and aminoalkyl radicals; and saturated or unsaturated,fused or non-fused, aromatic or non-aromatic (hetero)cyclic radicalsoptionally comprising at least one identical or non-identical heteroatomand optionally substituted; p and p′, which are identical or different,are each 0 or 1; and C_(sat) and C′_(sat), which are identical ordifferent, each represent an optionally cyclic, optionally substituted,linear or branched C₁-C₁₈ alkylene chains.